What would you then consider to be a “reliable source of information”? It sounds like your criteria for that are so high that it’s unlikely anything would reach up to that level. After all, should we ever trust any source as “the ultimate source of facts”? If all you wanted to point out was that noone can absolutely trust all of Wikipedia then fine I guess, but I would hope and doubt almost anyone here would have that mindset.
I would also say that many Wiki pages have a mix of overall neutral or positive-leaning text about the subject while e.g. a criticism section includes very good negative-leaning info. As an example, the Disney page (https://en.m.wikipedia.org/wiki/The_Walt_Disney_Company) has mostly neutral or positive information about the company, no doubt much of which is written by Disney fans. But it also has a good and sometimes savage criticism and controversies section. I have of course seen Wiki articles that are very skewed, but I’ve also seen very skewed research articles, lexicon entries etc. Wikipedia’s rules and the community of moderators trying to apply them as best as they can gives it a better chance than many other sources to correct in time at least.
Another point is that less and less counts as “the most generic of things”. The basic facts of biological development, evolution, even meteorology and chemistry are being increasingly questioned with nonsense. There is an immense value in all the hard work poured into improving, spreading and preserving that “generic” information. Wikipedia is a collective treasure shared with all the world. It shouldn’t be taken as gospel, nothing should like you point out, but despite its imperfections it’s worth so, so much.
Well, a considerable proportion of these users are likely trolls/propagandists trying to fracture the non-fascists even more. It’s worth remembering that many people who protested against the Democratic Party’s approach to Israel voted for them anyway because they thought it was still the better alternative. There are true assholes in the world too of course, including pro-palestine ones, there are in any movement, but there is a risk that they are exaggerated and made to seem more common through the work of propagandists.